One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(5,6,8,7)(9,10,14,20,15,21,32,19)(11,22,24,16,25,34,40,35)(12,26,28,33,29,39,27,17)(13,18,31,36,23,37,30,38)(1,2)(3,4)(9,11,14,24,15,25,32,40)(10,16,19,22,21,35,20,34)(12,23,27,31,29,13,28,30)(17,18,26,36,33,37,39,38)(5,6,8,7)(9,12,15,29)(10,17,21,33)(11,23,25,13)(14,27,32,28)(16,18,35,37)(19,26,20,39)(22,36,34,38)(24,31,40,30)(2,4)(5,7,8,6)(9,13)(10,18)(11,12)(14,31)(15,23)(16,33)(17,35)(19,38)(20,36)(21,37)(22,26)(24,28)(25,29)(27,40)(30,32)(34,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.